The custom of building a bonfire takes palce on 5 November and is a celebration of the failed plot by Guy Fawkes and other (Catholic) conspiritors to blow up the Houses of Parliament in 1605. It's still celebrated (most famously in the Sussex town of Lewes where they burn an effigy of the Pope, rather than Guy Fawkes himself)but nowadays it's often a large scale, communal/organised event. There are still plenty of bonfires and fireworks celebrations held in people's back gardens but they're (I reckon) not as common as when I was a child.

Dylan Thomas was Welsh and W.B. Yeats was Irish.

Oh, and yes all Americans are Yankees to us, but the word is usually shortened to 'Yanks.'